1. Field of the Invention
The present invention relates to a device for preventing unauthorized access to the hub of the propellers of boats or the like, in order to prevent unauthorized persons from removing the propeller from the boat's propulsion system.
2. Introduction and Description of Related Art
When motor boats or other watercraft are removed from the water and placed on a trailer and the trailer is left unattended, in a parking lot for example, the propellers of such water craft are vulnerable to theft. The thief simply has to remove the propeller retaining nut and then slide the propeller of the propeller shaft and the thief can make off with the propeller. Such boat propellers are costly to replace. Further, the delay due to the procurement of a replacement propeller, or the unavailability of a replacement propeller in certain areas, can spoil a carefully planned vacation, excursion, or fishing trip, at great financial cost to the boat user.
For these reasons, a myriad of anti-theft devices for marine propellers, or propeller locks as they are commonly known, have been proposed in the prior art.
For example, U.S. Pat. No. 5,613,386, issued to Jerry D. Mire, Sr. on Mar. 25, 1997, and U.S. Pat. No. 4,257,247, issued to Gary F. Sims on Mar. 24, 1981, disclose propeller locks having a cap portion that blocks access to the propeller retaining nut. The caps are held in place by arms that extend behind the propeller blades. Relative movement between the cap and the propeller is prevented by a cuff and padlock or a chain and padlock arrangement that engages the arms behind the propeller blades.
U.S. Pat. No. 5,417,093, issued to Martin D. Heiberg on May 23, 1995, discloses a propeller lock having a clamshell arrangement that fits around the concavely flared end of the propeller center-body to deny access to the propeller retaining nut. U.S. Pat. No. 5,246,345, issued to Michael J. Adams on Sep. 21, 1993, discloses a propeller lock having a clamshell arrangement that encloses the entire propeller to deny access to the propeller retaining nut. Both the Heiberg and the Adams devices use padlocks to prevent the unauthorized removal of the devices.
U.S. Pat. No. 4,645,422, issued to Donald Brushaber on Feb. 24, 1987, and U.S. Pat. No. 4,538,962, issued to Conrad L. McCain on Sep. 3, 1985, disclose propeller locks in the form of cone-shaped covers that prevent access to the propeller retaining nut. Both these devices require the replacement of the standard propeller retaining nut with a specialized propeller retaining nut. Both these devices use specialized tools keyed to matching patterns in the head of a bolt to prevent unauthorized removal of the cone-shaped cover.
U.S. Pat. No. 5,135,358, issued to James R. Myers on Aug. 4, 1992, discloses a cone-shaped cover that encloses the propeller retaining nut. The cone-shaped cover of Myers is retained in place by a plurality of resilient catches. The device of Myers is intended to render access to the propeller retaining nut more difficult, but this device cannot entirely prevent access to the propeller retaining nut.
U.S. Pat. No. 3,981,165, issued to Merol O. Wersinger on Sep. 21, 1976, discloses a propeller lock which fit around the inner propeller hub located within the center-body of the propeller and envelops the propeller retaining nut. The lock of Wersinger has two halves that fit together to form a jacket around the inner propeller hub. In the typical propeller the inner propeller hub is spaced from the interior surface of the propeller center-body creating an annular passage. The inner propeller hub is supported coaxially within the propeller center-body by a plurality of fins. One of the halves has a relief cut that allows a portion of that half to fit behind one of the fins. When the two halves are locked together, the device cannot be rotated such that the relief cut clears the fin. Thus, the device cannot be pulled off the propeller inner hub when the two halves are locked together. The two halves of the Wersinger device are locked together by a padlock.
U.S. Pat. No. 3,759,076, issued to John B. Reese on Sep. 18, 1973, discloses a propeller lock including a cup slidably mounted to a bar having a hooked end. The hook at the end of the bar is placed behind one of the fins supporting the propeller inner hub and the cup is slid into position covering the propeller retaining nut. A key operated, sliding lock is then moved into abutting contact with the cup and locked in place, thus capturing the cup between the propeller inner hub and the sliding lock.
U.S. Pat. No. 3,732,033, issued to Joseph E. Macchi on May 8, 1973, discloses a propeller lock including an adapter which mounts to the propeller shaft between the propeller and the propeller retaining nut. A cap fits the adapter and fully encloses the propeller retaining nut. The cap is secured to the adapter by a key-operated, cylinder lock. The cap fits a groove in the rim of the adapter, leaving the sides of the adapter exposed. The exposed adapter allows large pliers to be used to turn the adapter. There may be sufficient friction between the adapter and the propeller retaining nut to allow the propeller retaining nut to be turned as the adapter is turned, thus defeating the purpose of the lock.
U.S. Pat. No. 3,981,617, issued to Norbert W. Milewicz on Sep. 21, 1976, discloses a propeller lock for use with propellers having retaining nuts prevented from turning by a cotter pin. The standard propeller retaining nut is replaced by an elongated retaining nut having slots for the cotter pin. The end of the elongated nut projecting beyond the end of the propeller shaft, is configured for engagement by the tumblers of a cylinder lock. A retaining nut cover is placed over the elongated retaining nut and the retaining nut cover is held in place by a cylinder lock engaging the elongated retaining nut, thus preventing unauthorized access to the elongated retaining nut.
U.S. Pat. No. 4,715,783, issued to Mark W. Wade on Dec. 29, 1987, discloses an anti-theft device for marine propellers having two bars linked by a chain. The chain goes around the portion of the motor housing containing the bearings for the propeller shaft, positioning the two bars just above the propeller hub. A propeller blocking cylinder fits over the propeller hub and is locked to the bars to prevent unauthorized removal of the propeller. The Wade device can be easily defeated by the use of bolt cutters.
U.S. Pat. No. 5,469,721, issued to Stephen K. Pyle on Nov. 28, 1995, discloses an anti-theft device for marine propellers including a rigid case that completely surrounds the propeller and the lower portion of the motor housing. The case is locked with a padlock, making the device vulnerable to defeat by bolt cutters.
Canadian Patent Number 1,028,166, issued to Richard C. Slatford on Mar. 21, 1978, discloses a propeller lock having a washer that fits on the propeller shaft behind the propeller retaining nut. A split cup covers the retaining nut and engages the washer. The halves of the split cup are held together by a lock body that receives a pair of studs projecting from each half of the split cup.
None of the above described inventions employs a tongue having a through hole that is engaged by a grooved dowel to lock two halves of a protective cover together. None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.